cosh - Man Page

hyperbolic cosine function


Math library (libm, -lm)


#include <math.h>

double cosh(double x);
float coshf(float x);
long double coshl(long double x);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

coshf(), coshl():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE


These functions return the hyperbolic cosine of x, which is defined mathematically as:

cosh(x) = (exp(x) + exp(-x)) / 2

Return Value

On success, these functions return the hyperbolic cosine of x.

If x is a NaN, a NaN is returned.

If x is +0 or -0, 1 is returned.

If x is positive infinity or negative infinity, positive infinity is returned.

If the result overflows, a range error occurs, and the functions return +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL, respectively.


See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Range error: result overflow

errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.


For an explanation of the terms used in this section, see attributes(7).

cosh(), coshf(), coshl()Thread safetyMT-Safe


C11, POSIX.1-2008.


C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD.


In glibc 2.3.4 and earlier, an overflow floating-point (FE_OVERFLOW) exception is not raised when an overflow occurs.

See Also

acosh(3), asinh(3), atanh(3), ccos(3), sinh(3), tanh(3)

Referenced By

acosh(3), asinh(3), atanh(3), sinh(3), tanh(3).

The man pages coshf(3) and coshl(3) are aliases of cosh(3).

2023-10-31 Linux man-pages 6.7